Process for preparing a functional thin film by way of the chemical reaction among active species

ABSTRACT

A method for forming a functional silicon- or germanium-containing amorphous deposited film on a substrate which comprises a film-forming chamber having a film-forming space, a substrate holder and an electric heater for positioning the substrate in the film-forming chamber, an exhaust pipe in fluid communication with the film-forming chamber, a first gas-introducing portion for providing an active species (H), having an activation space for generating the active species (H), a microwave discharge supply source and a passage for providing a gaseous hydrogen-containing material into the activation space in order to produce the active species (H), a second gas-introducing portion for providing a gaseous silicon- or germanium-containing material (X), capable of reacting with the active species (H) to form a reaction product (HX) that is capable of forming the functional deposited film on the substrate, and a transportation path having a mixing space and a second microwave discharge energy supply source for promoting reaction with the active species.

This application is a continuation of application Ser. No. 08/121,196filed Sep. 15, 1993, now abandoned, which is a division of applicationSer. No. 08/046,906 filed Apr. 15, 1993, now U.S. Pat. No. 5,269,848,issued Dec. 14, 1993, which is a continuation of application Ser. No.07/771,535 filed Oct. 7, 1991, now abandoned, which is a continuation ofapplication Ser. No. 07/541,472 filed Jun. 25, 1990, now abandoned,which is a continuation of application Ser. No. 07/168,476 filed Mar.15, 1988, now abandoned.

FIELD OF THE INVENTION

This invention relates to a process for preparing a functional depositedthin film usable as an element member in various semiconductor devicesand an apparatus suited for practicing said process.

BACKGROUND OF THE INVENTION

There have been proposed a number of amorphous silicon (hereinafterreferred to as "A-Si") films for use as an element member insemiconductor devices, image input line sensors, image pickup devices orthe like. Some such films have been put to practical use.

Along with those amorphous silicon films, there have been proposedvarious methods for their preparation using vacuum evaporationtechnique, heat chemical vapor deposition technique, plasma chemicalvapor deposition technique, reactive sputtering technique, ion platingtechnique and light chemical vapor deposition technique.

Among those methods, the method using heat chemicals vapor depositiontechnique (hereinafter referred to as "CVD method") had been tried oncein various sectors, but nowadays it is not used because elevatedtemperatures are required and a practical deposited film can not beobtained as desired.

On the other hand, the method using plasma chemical vapor depositiontechnique (hereinafter referred to as "plasma CVD method") has beengenerally recognized as being the most preferred and is currently usedto manufacture amorphous silicon films on a commercial basis.

However, for any of the known A-Si films, even if it is such that it isobtained by plasma CVD method, there still remain problems unsolvedrelating to the film's characteristics, particularly electric andoptical characteristics, deterioration resistance upon repeated use anduse-environmental characteristics. The solutions to these problems mustcorrelate with its use as an element member for the foregoing devicesand also for other points such as its homogeneity, reproducibility andmass-productivity.

Now, although the plasma CVD method is widely used nowadays as abovementioned, it is still accompanied by problems since it is practicedunder elevated temperature conditions. Other problems are presented inthe process, including the apparatus to be used.

Regarding the former problems, because the plasma CVD method ispracticed while maintaining a substrate at elevated temperature, thekind of the substrate to be used is limited to those which do notcontain a material such as a heavy metal, which can migrate andsometimes cause changes in the characteristics of the deposited film tobe formed. Secondly, the substrate thickness is likely to be varied onstanding in the plasma CVD method. Therefore, the resulting depositedfilm, lacking in uniformity of thickness and in homogeneity ofcomposition, can exhibit changed characteristics.

Regarding the latter problems, the operation conditions to be employedunder the plasma CVD method are much more complicated than the known CVDmethod, and it is extremely difficult to generalize them.

That is, there already exist a number of variations even in thecorrelated parameters concerning the temperature of a substrate, theamount and the flow rate of gases to be introduced, the degree ofpressure and the high frequency power for forming a layer, the structureof an electrode, the structure of a reaction chamber, the rate of flowof exhaust gases, and the plasma generation system. Besides saidparameters, there also exist other kinds of parameters. Under thesecircumstances, in order to obtain a desirable deposited film product, itis required to choose precise parameters from a great number of variedparameters. Sometimes, serious problems occur. Because of the preciselychosen parameters, a plasma is apt to be in an unstable state. Thiscondition often invites problems in a deposited film to be formed.

And for the apparatus in which the process using the plasma CVD methodis practiced, its structure will eventually become complicated since theparameters to be employed are precisely chosen as above stated. Wheneverthe scale or the kind of the apparatus to be used is modified orchanged, the apparatus must be so structured as to cope with theprecisely chosen parameters.

In this regard, even if a desirable deposited film should befortuitously mass-produced, the film product becomes unavoidably costlybecause (1) a heavy initial investment is necessitated to set up aparticularly appropriate apparatus therefor; (2) a number of processoperation parameters even for such apparatus still exist and therelevant parameters must be precisely chosen from the existing variousparameters for the mass-production of such film. In accordance with suchprecisely chosen parameters, the process must then be carefullypracticed.

In order to prepare a desired functional A-Si film without the aboveproblems, there has been proposed a method by way of the chemicalreaction among gaseous raw material and active species or by way of thechemical reaction active species using a fabrication apparatus as shownin FIG. 1 or another fabrication apparatus as shown in FIG. 2.

The fabrication apparatus of FIG. 1 comprises a film forming chamber102, a film forming raw material gas transportation pipe 105, an activespecies (I) generation region 108 and a pipe portion 109 having a spaceB for mixing a film forming raw material gas and an active species (I)and transporting a gaseous mixture of them into the film formingchamber.

The film forming chamber 102 has a film forming space A in which asubstrate holder 103 for substrate 104 having electric heater 110 beingconnected to a power source (not shown) by means of lead wires (notshown) is installed.

The film forming chamber 102 is provided with an exhaust pipe 101'connected through a main valve (not shown) to an exhaust pump 101, andthe exhaust pipe is provided with a subsidiary valve (not shown) servingto break the vacuum in the film forming chamber 102. Numeral 111 standsfor a vacuum gauge to monitor the inner pressure of the film formingspace A.

The active species (I) generation region 108 comprises pipe portion 106having an active species (I) generation space C with which a microwaveenergy applying applicator 107 is provided, and the microwaveintroducing applicator is connected to a microwave power source. To oneend of the pipe portion 106, an active species (I) raw material gas (H₂)feed pipe extended from a reservoir for said gas is connected. The otherend of the pipe portion 106 is joined with the film forming raw materialgas transportation pipe 105 at the upstream region of the pipe portion106.

The pipe portion 106 is open at its downstream end in the film formingspace A. To the end portion of the film forming raw material gastransportation pipe 105, a film forming raw material gas (SiF₄) feedpipe extended from a reservoir for said gas is connected.

The fabrication apparatus of FIG. 2 is a partial modification of thefabrication apparatus of FIG. 1, and the modified part is that the filmforming raw material gas transportation pipe 105 in FIG. 1 is replacedby an active species (II) generation region 201. In the fabricationapparatus of FIG. 2, the active species (II) generation region 201comprises pipe portion 105 having an active species (II) generationspace D with which a microwave energy applying applicator 202 isprovided, and the microwave introducing applicator 202 is connected to amicrowave power source (not shown).

The film forming process for preparing a A-Si thin film using thefabrication apparatus of FIG. 1 is carried out, for example, in thefollowing way.

That is, the air in the film forming chamber, the film forming rawmaterial gas transportation pipe 105 and t he precursor generation spaceC is evacuated by opening the main valve of the exhaust pipe 101' tobring the chamber and other spaces to a desired vacuum. Then the heater110 is activated to uniformly heat the substrate 104 to a desiredtemperature, and it is kept at this temperature. At the same time, SiF₄gas is fed at a desired flow rate into the transportation pipe 105 andthen into the film forming space A through the space B. Concurrently, H₂gas is fed at a desired flow rate into the active species (I) generationspace C and then into the film forming space A through the space B.After the flow rates of the two gases became stable, the vacuum of thefilm forming space A is brought to and kept at a desired value byregulating the main valve of the exhaust pipe 101'.

After the vacuum of the film forming space A becomes stable, themicrowave power source is switched on to apply a discharge energy of adesired power into the active species (I) generation space C through themicrowave energy applying applicator 107.

In this event, H₂ gas is activated with the discharge energy to generateactive species (I), which are successively flowed into the space B, thenmixed with SiF₄ gas flowed from the transportation pipe 105 therein, andtransported into the film forming space A while being chemicallyreacted. The gaseous reaction mixture thus introduced is flowed in thespace surrounding the surface of the substrate 104 being maintained at adesired temperature in the film forming space A and decomposed tothereby cause the formation of a A-Si:H:F thin film on the substrate.

The chemical reactions to cause the formation of said A-Si:H:F thin filmin the case of the above process using the fabrication apparatus of FIG.1 is considered to be progressed in the following ways.

(a) Reaction in the active species (I) generation space C:

H₂ →2·H(·H means hydrogen radical)

(b) Reaction in the space B:

(i) ·H+SiF₄ →reaction product (1)

(ii) ·H+the reaction product I→reaction product (2)

The above-mentioned reaction product (1) is a molecule or a radicalwhich are not sufficiently reduced and which are highly volatile, and itdoes not directly contribute to the formation of said A-Si:H:F thin filmas it is. The above-mentioned reaction product (2) is a productresulting from the reaction product (1) being further reduced with thehydrogen radical (·H), and it contributes to the formation of saidA-Si:H:F thin film on the substrate 104 in the film forming space A.

The exact mechanism of how the formation of said A-SiH:F thin film iscaused onto the surface of the substrate is not clarified yet. Howeverit is thought that the reaction product (2) as it flows into the filmforming space A will be decomposed by the action of a thermal energy inthe space surrounding the surface of the substrate being maintained withan elevated temperature and some of the reaction product (2) willcollide against said surface of the substrate to thereby decompose intoneutral radical particles, ion particles, electrons, etc. The chemicalreactions among them will result in formation of said A-Si:H:F thin filmon the surface of the substrate.

However, there still remain unsolved problems in the case of the aboveprocess using the fabrication apparatus of FIG. 1 That is, as mentionedin the above reactions (b), hydrogen radical (·H) as generated in theactive species (I) generation space C will be consumed twice for thereaction (i) and for the reaction (ii) and because of this, the amountof the reaction product (2) to be produced in the space B depends uponthe amount of the remaining hydrogen radical. However, in the case ofthe known process using the fabrication apparatus of FIG. 1, the amountof such hydrogen radical to be directed to forming the reaction product(2) is not sufficient so that the reaction product (2) cannot besufficiently produced and because of this, it is almost impossible tostably and efficiently form a desired deposited film at a highdeposition rate and with a high utilization efficiency of raw materialgas.

In addition to this problem, there are also other problems for theprocess using the fabrication apparatus of FIG. 1. That is, H₂ gas isnot efficiently consumed to generate hydrogen radical in the activespecies (I) generation space C and as a result , the amount of thehydrogen radical to be generated therein eventually becomesinsufficient. And the hydrogen radical as generated will often collideagainst the inner wall face having roughness and occasionally havingforeign deposits thereon, and if such situation happens, the radicalbecomes deactivated to be neutral as it is transported to space B.Therefore, there often occurs changes in the amount of the hydrogenradical to arrive in the space B, which result in bringing about changesin the amounts of the reaction product (1) and because of this, thedeposition rate of a deposited film to be formed will be changed and itwill become difficult to stably obtain a desired deposited film of anuniform film quality.

As for the film forming process for forming a A-Si:H:F thin film usingthe fabrication apparatus of FIG. 2, it is carried out in the same wayas in the case of the above process using the fabrication apparatusexcept that a microwave discharge energy of a desired power is appliedinto the active species (II) generation space D to thereby generateactive species (II) from SiF₄.

The chemical reactions to cause the formation of said A-Si:H:F film i nthe case of the process using the fabrication apparatus of FIG. 2 isconsidered to be progressed in the following ways.

(a) Reaction in the active species (I) generation space C:

H₂ →2·H (·H means hydrogen radical)

(b) Reaction in the active species (II) generation space D:

SiF₄ →decmposed product such as SiF₂ ^(*), SiF₃ ^(*), Si^(*), SiF₂, etc.

(c) Reaction in the space B:

·H+decomposed product→reaction product (3)

And the exact mechanism of how the formation of said ASi:H:F thin filmis caused onto the surface of the substrate is not clarified yet.

However, it is thought that the reaction product (3) as it flows intothe film forming space A will be decomposed by the action of a heatenergy in the space surrounding the surface of the substrate beingmaintained with an elevated temperature and some of the reaction product(3) will collide against said surface of the substrate to therebydecompose into neutral radical particles, ion particles, electrons, etc.The chemical reactions among them will result in the formation of saidA-Si:H:F thin film on the surface of the substrate.

However, even for this process, there still remains unsolved problems.That is, undesired changes often occur on the deposition rate andbecause of this, it is difficult to stably and efficiently obtain adesired A-Si:H:F thin film of an uniform film quality with a highdeposition rate and with a high raw material gas utilization efficiency.In addition to this problem, there are also other problems. That is, aswell as in the case of process using the fabrication apparatus of FIG.1, H₂ gas is not efficiently consumed to generate hydrogen radical (·H)in the active species (I) generation space C and the amount of thehydrogen radical to be generated therein eventually becomesinsufficient. And the hydrogen radical as generated will often collideagainst the inner wall face having roughness and occasionally havingforeign deposits thereon and hence, while the radical is beingtransported to the space B it becomes deactivated to be neutral. Andthere often occurs changes in the amount of the hydrogen radical toarrive in the space B, which results in bringing about changes in theamounts of the reaction products (3). Further, certain amount of thedecomposed product will be left without being consumed in theabove-mentioned reaction (c) and it is flowed into the film formingspace A. Because of this, the decomposed product that flowed into thefilm forming space A will have undesired influence on the resultingdeposited film.

In view of the above, there is now an increased demand for providing animposed process that makes it possible to stably and efficientlymass-produce a desirable A-Si thin film of good film quality which has awealth of practically applicable characteristics with a high depositionrate and with a high raw material gas utilization efficiency. Besidessilicon, there is a similar situation for other kinds of non-singlecrystal functional materials such as polycrystal silicon, siliconnitride, silicon-germanium, silicon carbide, and silicon oxide films.

SUMMARY OF THE INVENTION

The present inventions have conducted extensive studies in order tosolve the problems in the aforementioned known process and in order todevelop an improved process for effectively and simply preparing afunctional deposited film such as a A-Si thin film which has a wealth ofmany practically applicable characteristics and which is usable as anelement member in various semiconductor devices.

As a result, the present inventors have finally found a process thatenables stable and efficient formation of a desirable functionaldeposited film usable as an element member in various semiconductordevices by the simple procedures detailed below.

It is therefore an object of this invention to provide an improvedprocess for preparing a high quality functional deposited film free fromcontamination of foreign matters and having a wealth of many practicallyapplicable characteristics and which is suited for use in varioussemiconductors at a high deposition rate and with a high raw materialgas utilization efficiency.

Another object of this invention is to provide an improved process forpreparing the foregoing functional deposited film by introducing amaterial capable of supplying atoms to be constituents for said film anda gaseous active species reactive with said material into a separatespace isolated from a film forming space, starting chemical reactionamong them and concurrently applying a reaction promotion energy intosaid separate space to thereby form a gaseous product capable ofcontributing to the formation of said film, and introducing theresulting gaseous product into said film forming space having asubstrate being maintained at an elevated temperature to thereby formsaid film on the surface of said substrate at a high deposition ratewithout the use of plasma discharge in said film forming space.

A further object of this invention is to provide an apparatus suitablefor practicing said process.

According to one aspect of this invention, there is provided an improvedprocess for preparing a desirable functional deposited film,characterized in that the chemical reaction among a material (X) capableof supplying atoms to be constituents for said film and a gaseous activespecies (H) generated from a gaseous chemical substance (Y) which isreactive with said material (X) is carried out while applying a reactionpromotion energy to produce a gaseous product (HX) capable ofcontributing to the formation of said film in a space isolated from afilm forming space and said gaseous product (HX) is introduced into saidfilm forming space being maintained with a desired vacuum and having asubstrate being kept with an elevated temperature to thereby form saidfilm on the surface of the substrate at a high deposition rate and witha high raw material gas efficiency without the use of plasma discharge.

According to a further aspect of this invention, an apparatus isprovided which is suitable for practicing the above process,characterized by comprising an activation space (1), a first introducingmeans for the foregoing gaseous substance (Y), a second introducingmeans for the foregoing material (X), a means to apply an activationenergy onto the foregoing gaseous chemical substance (Y) as introducedin said activation space (1) to generate the foregoing active species(H), a transportation means having a mixing space (2) to which saidfirst introducing means and said second introducing means beingconnected, a means to apply a reaction promotion energy onto a mixtureof the foregoing material (X) and the foregoing active species (H) asintroduced in said mixing and transportation space (2), and a filmforming space being connected to said mixing and transportation space(2).

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic explanatory diagram of a known apparatus for thepreparation of a functional deposited film.

FIG. 2 is a schematic explanatory diagram of another known apparatus forthe preparation of a functional deposited film.

FIG. 3, FIG. 4, FIG. 5 and FIG. 6 are schematic explanatory diagrams ofapparatuses suitable for carrying out the process for the preparation ofa functional deposited film according to this invention.

DESCRIPTION OF THE INVENTION

In a typical embodiment of the process for preparing a functionaldeposited film according to this invention, the formation of theforegoing gaseous product (HX) capable of contributing to the formationof a functional deposited film (hereinafter referred to as "film formingmaterial (HX)") is caused by introducing a material (X) capable ofsupplying atoms to be constituents for the resulting functionaldeposited film and an active species (H) chemically reactive with saidmaterial (X) into a mixing and transportation space being isolated froma film forming space and mixing them during their transportation towardthe film forming space while purposely applying a reaction promotingenergy thereinto. The film forming material thus formed is successivelytransported into the film forming space having a substrate beingmaintained at an elevated temperature therein and it is decomposed in aspace surrounding the surface of the substrate to thereby cause theformation of a functional deposited film on the surface of thesubstrate.

As the material (X), any material may be employed as long as it is suchthat supplies atoms to be constituents for an objectives functionaldeposited film to be formed and that chemically reacts with the activespecies (H) to cause the formation of an objective film forming material(HX) in the mixing and transportation space. And it is desired for thematerial (X) to be introduced in a gaseous state into the mixing andtransportation space for the reason that when it is a gaseous material,its admixture with the active species (H) and the chemical reactionamong them are effectively carried out and the formation of the filmforming material (HX) is effectively caused.

Further, as for the material (X), it is desired to be in an activatedstate when introduced into the mixing and transportation space for thereason that the admixture of the material (X) with the active species(H) and the chemical reaction among them are further effectivelypromoted and as a result, the formation of the film forming material(HX) is further effectively promoted.

However, the material (X) is not always necessary to be in an activatedstate, and it may be such that is of a so-called neutral state.

Details in this respect will be explained at later stage .

As the material (X) usable in this invention, there may be illustratedcompounds containing Group IV atoms of the Periodic Table which are inthe gaseous state or can be easily made to be in the gaseous state.

Desirable examples of them are such as expressed by the followinggeneral formulas (1) or (2) in which a highly electron attractive atomor atomic factor, or a polar group being bonded to Group IV atom:

    T.sub.n X.sub.2n+2                                         (1),

    (TX.sub.2).sub.n                                           (2)

wherein n is an integer of 1, 2 or 3, T is one or more members selectedfrom the group consisting of carbon atom (C), silicon atom (Si),germanium atom (Ge) and tin atom (Sn), and X is one or more selectedfrom the group consisting of fluorine (F), chlorine (Cl), bromine (Br)and iodine (I).

Specific examples which are used in the neutral state are SiF₄, Si₂ F₆,Si₃ F₈, Si₂ Cl₆, SiF₂ Cl₂, Si₂ F₄ Cl₂, SiBr₂ F₂, Si₂ Br₆, SiCl₄, Si₂ I₆,GeF₄, GeCl₄, CF₄, CBr₄, C₃ F₈, SnF₄, SnCl₄, SnBr₄, (SiF₂)₃, (SiF₂)₄,(SiF₂)₅, (Sif₂)₆, (GeF₂)₄, (GeF₂)₅, (GeF₂)₆, etc.

Other than these compounds, it is possible to use such compounds as SiH₂(C₆ H₅)₂ and SiH(CN)₂ in accordance with the end use of the resultingdeposited film.

Among these compounds, fluorine containing compounds are desirable inthis invention.

In a preferred embodiment of the material (X) to be used in theactivated state in this invention, there is used such that one or moreof the above-mentioned compounds have been made to be in the activatedstate by applying an energy such as light energy or heat energy thereonor such that is generated as a result of applying the above energy ontoone or more of the above-mentioned compounds.

For instance, in the case of forming a silicon containing depositedfilm, it is desired to use radicals such as SiF₂ ^(*) and the like whichare generated by the glow discharge in the above-mentioned fluorinecontaining compound. Likewise, radicals such as GeF₂ ^(*) are desired inthe case of forming a germanium containing deposited film.

As for the active species (H) to be used in this invention, it can begenerated by applying an appropriate activation energy onto relevantcompound (Y). As the raw material to generate such active species (H),there may be illustrated those which are in the gaseous state or can beeasily made to be in the gaseous state.

Desirable examples of them are H₂ or a member of compounds having thefollowing general formulas (3) or (4):

    T.sub.n H.sub.2n+2                                         (3),

    TH.sub.n X.sub.4-n                                         (4)

wherein n is an integer 1, 2 or 3, and T and X have the same meanings asin the cases of the foregoing general formulas (1) and (2).

Specific examples of the compounds having the general formulas (3) and(4) are SiH₄, Si₂ H₆, Si₃ H₈, GeH₄, Ge₂ H₆, Ge₃ H₈, CH₄, C₂ H₆, C₃ H₈,SnH₄, SiH₂ Cl₂, SiH₃ Cl, SiHF₃, SiHCl₃, SiHBr₃, etc.

By the way, in this invention, the term "activation" at the time whenthe compound (Y) is activated to generate the active species (H) meansthat the compound (Y) is dissociated, ionized or radicalized, and amongthose resulted in these cases, such in the activated state is identifiedas the active species (H).

In a preferred embodiment with respect to the active species (H) in thisinvention, it is desired to use an active species containing hydrogenatom (H), or in particular, hydrogen radical (·H).

As the reaction promotion energy to be applied on the material (X) andthe active species (H) being mixed while being chemically reacted in themixing and transportation space in this invention, there may beillustrated light energy, heat energy, radiated heat energy, dischargeenergy and the like, among these energies, discharge energy being mostpreferred.

As the discharge energy, a high frequency discharge energy of radiofrequency (RF) region or of microwave frequency region is desirable.Specific examples are a radio frequency discharge energy of 13.56 MHzand a microwave discharge energy of 2.45 GHz.

As for the film forming material (HX) to be resulted from the material(X) and the active species (X) in this invention, it is a memberselected from the group consisting of the following (i) to (iv)materials or a mixture of two or more of them:

(i) a mixed body comprised of the material (X) and the active species(H);

(ii) a reaction product of the material (X) and the active species (H);

(iii) a dissociated product of the material (X) or a reaction productthereof; and

(iv) a dissociated product of the active species (H) or a reactionproduct thereof

And in any case, such film forming material contains one or more kindsof factors capable of directly contributing to the formation of anobjective functional deposited film.

In this invention, when the foregoing reaction promotion energy isapplied into the mixing and transportation space, it also serves,besides serving to promote the chemical reaction among the material (X)and the active species (H), to excite the above mixed body (i), promotethe chemical reaction of causing the above reaction product (ii) and theabove dissociated products (iii) and/or (iv), or further excite theabove reaction product (ii) and the above dissociated products (iii)and/or (iv).

According to this invention, as above described, the film formingmaterial (HX) contains one or more kinds of factors capable of directlycontributing to the formation of an objective deposited film. And thereaction promotion energy as applied into the mixing and transportationspace serves to promote the chemical reaction of the reaction system andto increase said factors in the film forming material (HX) so that thefilm forming material (HX) effectively supplies atoms to be constituentsfor an objective deposited film to be formed and/or chemical speciescontaining such atoms onto the surface of a substrate being maintainedat an elevated temperature in the film forming space.

Because of this, this invention makes it possible to repeatedly obtainan objective functional deposited film excelling in the quality andhaving a wealth of many practically applicable characteristics at animproved deposition rate and with an improved raw material gasutilization efficiency.

Moreover, in this invention, as the film forming space is isolated fromthe mixing and transportation space, an objective deposited film may beeffectively formed on the surface of the substrate without having anyundesired influences of the reaction promotion energy as applied intothe mixing and transportation space. That is, there is not any or merelya slight occasion for said objective deposited film to be formed to haveinfluence of bonbardment which will be resulted from ion parceticsgenerated in the case of using discharge energy, of over-heat which willbe caused in the case of using heat energy or of light fatigue whichwill be caused in the case of using light energy.

As fort he conditions for generating the active species (H) by applyingan activation energy onto the foregoing compound (Y) as introduced inthe active species (H) generation space, they are properly determineddepending upon the kind of a deposited film to be formed, the kind ofthe material (X) to be used, the kind of the active species (H) to beused, etc.

However, the flow rate of the foregoing compound (Y) to be fed into theactive species (H) generation space is preferably 1 to 500 SCCM and morepreferably, 10 to 300 SCCM.

As for the inner pressure of the active species (H) generation space inthe case of generating the active species (H), it is preferably 5×10⁻⁵Torr and more preferably, 1×10⁻⁴ to 5 Torr.

In the case where it is necessary to heat the foregoing compound (Y) inthe active species (H) therefrom by applying an activation energythereonto, appropriate heating method and a desired temperature areproperly selected so that the active species (H) generating reaction ofthe compound (Y) with the application of an activation energy may beeffectively caused in the active species (H) generation space.

As such heating method, there can be illustrated a method of indirectlysupplying heat energy through the circumferential wall of the activespecies (H) generation space using electric coil heater or electricplate heater being mounted on the outer surface of said circumferentialwall, a method of directly supplying heat energy onto the compound (Y)using one of said heaters being mounted within the active species (H)generation space, other than these heating methods, a known radiationheating method and a known microwave heating method. As for the heatingtemperature, a temperature of 50° to 1500° C. may be s electivelyemployed upon the situation. However, in general, it is preferably 80°to 1200° C., and most preferably 80° to 1000° C.

As the activation energy to be applied in the case of generating theactive species (H), any of the energies as above illustrated for thereaction promotion energy may be selectively employed. Among thoseenergies, a high frequency discharge energy is most desirable. Specificexamples of the high frequency discharge energy are a radio frequency(RF) discharge energy of 13.56 MHz and a microwave discharge energy of2.45 GHz.

In the case of employing light energy as the activation energy togenerate the active species (H) from the compound (Y) in the activespecies (H) generation space, an appropriate light energy applyingsource such as high-pressure mercury-vapor lamp, tungsten halogen lamp,laser beam source or t he like is so provided withe active species (H)generation space that a proper light energy is effectively applied intothe active species (H) generation space from the outside.

In this case, it is necessary for the wall member of the active species(H) generation space to be made of a light transmissive material atleast with its part through which the light energy may be applied intothe active species (H) generation space. As such light transmissivematerial, there may be illustrated quartz glass, transparent ceramics,etc.

In the case of introducing the material (X) into the mixing andtransportation space, the material (X) is supplied from the material (X)supplying space being situated in the upstream side of the mixing andtransportation space.

In a preferred embodiment of this invention, as the material (X) to beintroduced into the mixing and transportation space, it is desired touse the foregoing activated state material (X) (hereinafter referred toas "material(X^(*))") and other materials derived from the material (X)(hereinafter referred to as "material (X) derivative") which aregenerated by applying an activation energy onto the material (X),namely, one or more raw materials selected from the compoundsrepresented by the above-mentioned general formulas (1) and (2).

In this case, the material (X) supplying space is desired to be sostructured to have an activation space to generate the above material(X^(*)) or/and the above material (X) derivative (hereinafter referredto as "material (X) activation space") with which a means of applyingsaid activation energy being provided. As for the source for suchactivation energy, an appropriate energy source is selectively useddepending upon the kind of the material (X) to be used and theactivation conditions to be employed. However, as such activationenergy, any of those to be employed in the case of generating the activespecies (H) may be properly and selectively employed. Among suchactivation energies, a high frequency discharge energy such as a radiofrequency (RF) discharge energy of 13.56 MHz and a microwave dischargeenergy of 2.45 GHz is particularly desireble.

In the case of employing such high frequency discharge energy in orderto generate the foregoing material (X^(*)) or/and the foregoingmaterial(X) derivative in the material (X) activation space, itsdischarge power is properly determined in accordance with the kind of araw material selected from the compounds represented by theabove-mentioned general formula (1) and (2) to be used, the kind of anapparatus to be used, etc. However, it is preferably 50 to 100 W/cm² andmore preferably, 80 to 800 W/cm².

As for the flow rate for the material (X) to be fed into the material(X) activation space, it is preferably 1 to 500 SCCM, and morepreferably, 10 to 300 SCCM.

In this embodiment, a gaseous material to be resulted as a result ofapplying an activation energy in the material (X) activation space willbe usually a gaseous mixture of the material (X^(*)), the material (X)derivative and the material (X). Such gaseous mixture thus resulted willbe successively transported into the mixing and transportation spacewhere it will mixed and reacted with the active species (H) asconcurrently introduced therein to while receiving the action of theforegoing reaction promotion energy.

In this case, in addition to said gaseous material, it is possible toindependently introduce the material (X) into the mixing andtransportation space through an appropriate feeding means.

As the reaction promotion energy to be employed in this case, a highfrequency discharge energy as such mentioned above is most appropriate,and its discharge power is preferably 10 to 800 W/cm², and morepreferably, 30 to 500 W/cm².

In this invention, as for the amount of the material (X), the amount ofthe aforesaid gaseous mixture or the sum amount of the aforesaid gaseousmixture and the material (X) to be introduced into the mixing andtransportation space and also as for the amount of the active species(H) to be introduced into the mixing and transportation space, they areproperly determined in accordance with the shape, size and arrangementof the mixing and transportation space, the kinds of the raw materialsto be used, the kind of the reaction promotion energy to be employed,etc.

However, in any case, the flow ratio of the former raw materialrepresented by the material (X) to the latter raw material, that is, theactive species (H) is adjusted to preferably 1/100 to 100/1, or morepreferably, to 1/50 to 80/1.

As for the inner pressure of the film forming space at the time when adeposited film is formed on a substrate in this invention, it isproperly determined depending upon the kind of said film to be formedand the characteristics desired for the resulting film.

However, it is preferably 0.01 to 10 Torr, and more preferably, 0.05 to8 Torr.

As for the substrate temperature, it is property determined alsodepending upon the above related items.

However, it is preferably 80° to 450° C., and more preferably, 100° to350° C.

In order to carry out the above-mentioned process for preparing afunctional deposited film according to this invention, there is used anappropriate apparatus suited therefor as much shown in FIG. 3, FIG. 4,FIG. 5 or FIG. 6.

FIG. 3 is a schematic explanatory diagram of a first representativeapparatus according to this invention which is a modification of theknown apparatus shown in FIG. 1. Therefore, in FIG. 3, there are usedthe same numerals and the same as in FIG. 1 for the unchanged parts. Asshown in FIG. 3, the modified part 109 of the known apparatus of FIG. 1comprises a mixing and transportation pipe 301 having a space E formixing and transporting the material (X) and the active species (H) asflowed therein to while effectively causing the chemical reaction amongthem with the action of a reaction promotion energy (for example, a highfrequency discharge energy) applied through the circumferential wall ofthe mixing and transportation pipe 301 from a reaction promotion energyapplication means, that is, a microwave introducing applicator 302 of amicrowave 304 transmitted from a microwave power source (not shown)which is mounted with the outer face portion of the circumferential wallof the mixing and transportation pipe 301.

In more detail of this respect, for example, a microwave 304 of 2.45 GHzin frequency is applied with a desired power through the microwaveintroducing applicator 302 into the mixing and transportation space E tothereby cause a discharge in a gaseous atmosphere containing thematerial (X) and the active species (H) therein.

At the upstream portion of the mixing and transporation pipe 301, thereare jointed a material (X) transportation pipe 105 and an active species(H) generation and transportation pipe 106 so as to allow a material (X)and an active species (H) to be flowed into the space E.

Numeral 108 stands for a active species (H) generation region whichcomprises the active species (H) generation and transportation pipe 106to which a feed pipe for a raw material gas for the generation of theactive species (H) extended from a reservoir (not shown) and anactivation energy introducing applicator 107 of an activation energysource 303 (for example, a high frequency power) from a power source(not shown). To the material ((X) transportation pipe 105, there isconnected a feed pipe of a raw material gas for the material (X)extended from a reservoir (not shown).

Numeral 102 stands for a film forming chamber into which the mixing andtransportation pipe 301 being open at its down stream end.

The film forming chamber 102 has a film forming space A in which asubstrate holder 103 for substrate 104 having electric heater 110 beingconnected to a power source (not shown) by means of lead wires (notshown) is installed.

The film forming chamber 102 is provided with exhaust pipe 101'connected through a main valve (not shown) to an exhaust pump 101, andthe exhaust pipe is provided with a subsidiary valve (not shown) servingto break the vacuum in the film forming chamber 102. Numeral 111 standsfor a vacuum gauge to monitor the inner pressure of the film formingspace A.

FIG. 4 is a schematic explanatory diagram of a second representativeapparatus according to this invention which is a modification of theknown apparatus of FIG. 2. The modification is that the pipe portion 109having the space B in the known apparatus of FIG. 2 is replaced by amixing and transportation pipe 301 having a space for mixing andtransporting the material (X) and the active species (H) as flowedtherein to while effectively causing the chemical reaction among themwith the action of a reaction promotion energy (for example, a highfrequency discharge energy) applied through the circumferential wall ofthe mixing and transportation pipe 301 from a reaction promotion energyapplication means, that is, a microwave introducing applicator 302 of amicrowave 304 transmitted from a microwave power source (not shown)which is mounted with the outer face portion of the circumferential wallof the mixing and transportation pipe 301.

And other parts of the apparatus shown in FIG. 4 according to thisinvention has the same structure as the apparatus shown in FIG. 3.

FIG. 5 is a schematic explanatory diagram of a third representativeapparatus according to this invention which is a modification of theapparatus of FIG. 4.

The modified is that the microwave introducing applicator 302 isreplaced by a tungusten filament 502 of supplying an incandescenceenergy as the reaction promotion energy. That is, in FIG. 5, numeral 501stands for a mixing and transportation pipe having a mixing andtransportation space F. The tungusten filament 502 is provided in thespace F. The tungusten filament 502 is electrically connected throughlead wires to a power source (not shown).

FIG. 6 is a schematic explasnatory diagram of a fourth representativeapparatus according to this invention.

The fabrication apparatus of FIG. 6 comprises a film forming chamber 602having a film forming space A and a film forming raw material gastransportation pipe 605 being open into the film forming space A at itsterminal end.

The film forming chamber 602 is provided with an exhaust pipe 601'connected through a main valve (not shown) to an exhaust pump 601, andthe exhaust pipe is provided with a subsidiary valve (not shown). Thefilm forming chamber 602 is also provided with a vacuum gauge 611 toserve for monitoring the inner pressure of the film forming space A. Inthe film forming space A of the film forming chamber 602, there isprovided a holder 603 for a substrate 604, in which an electric heater603' being electrically connected to a power source by means of leadwires (not shown) is installed.

The transportation pipe 605 has a raw material gas activation region 608at its upstream portion and a mixing region 610 at its downstreamportion. The mixing region has a space E serving for mixing andtransporting the active species (H) and the material (X) as flowedtherein to with the action while effectively causing the chemicalreaction among them with the action of a reaction promotion energy (forexample, a high frequency discharge energy) applied through thecircumferential wall of the transportation pipe 605 from a reactionpromotion energy application means, that is, a microwave introducingapplicator 609 of a microwave transmitted from a microwave power source(not shown) which is mounted with the outer face portion of thecircumferential wall of the transportation pipe 605 lying in the mixingregion 610. The space E in the mixing region 610 is so provided as toterminate before the opening of the transportation pipe 605 into thefilm forming space A with leaving a desired non-plasma space 612. Theupstream portion of the transportation pipe 605 in the activation region608 has a double conduit structure having a middle conduit 606 fortransporting the material (X) being horizontally situated therein andbeing open in a space adjacent to the space E at its end. To the otherend of the middle conduit 606, there is connected a feed pipe extendedfrom a reservoir for the material (X) (this part is not shown). Themiddle conduit 606 has a space D which serves for transporting a gaseousraw material of the material (X) and optionally for activating saidmaterial. C indicates an outer cylindrical circular space formed by thecircumferential wall of the transportation pipe 605 lying in theactivation region 608 and the outer wallface of the circumferential wallof the middle conduit 606, which serves not only for transporting agaseous raw material (Y) through a feed pipe therefor being extendedfrom a reservoir for said material (Y) (this part is not shown) but alsofor generating the active species therefrom with the action of anactivation energy applied through the circumferential wall of the abovetransportation pipe 605 from an activation energy application means(applicator) 607 which is mounted with the outer wallface portion of thecircumferential wall of the above transportation pipe 605.

In the apparatus of FIG. 6 of this invention, it is possible to activatea gaseous raw material for the active species (H) and a gaseous rawmaterial for the material (X) in the activated state or in other states.In this case, the middle conduit 606 is made such that is made of andielectric material such as quartz.

And in the apparatus of FIG. 6 of this invention, it is possible to usethe middle conduit 606 for a gaseous raw material and the remaining fora gaseous raw material for the material (X).

The film formation process to form a A-Si:H:F deposited thin film o nthe substrate 104 using the first representative fabrication apparatusof FIG. 4 according to this invention is carried out, for example, inthe following way.

That is, the film forming chamber 102, the film forming raw material gastransportation pipe 105 and the active species (H) gene ration space Cis evacuated by opening the main valve of the exhaust pipe 101' to bringthe chamber and other spaces to a desired vacuum. Then the heater 110 isactivated to uniformly heat the substrate 104 to about 300° C., and itis kept at this temperature. At the same time, SiF₄ gas is fed at a flowrate of 30 SCCM into the transportation pipe 105 and then into the filmforming space A through the space E. Concurrently, H₂ gas is fed at aflow rate of 20 SCCM into the active species (H) generation space C andthen into the film forming space A through the space E. After the flowrates of the two gases became stable, the vacuum of the film formingspace A is brought to and kept at 0.5 Torr by regulating the main valveof the exhaust pipe 101'.

After the vacuum of the film forming space A became stable, themicrowave power source is switched on to apply a discharge energy of adesired power into the active species (H) generation space C through themicrowave energy applying applicator 107.

Concurrently, the microwave power source is switched on to apply adischarge energy of a desired power into the space E through themicrowave energy applying applicator 302.

In this case, the active species (H) i.e. H^(*) (hydrogen radical),deactivated material, such as H₂ and H caused therefrom duringtransportation and the remaining unactivated H₂ gas arrive in the spaceE, where they are mixed with SiF₄ as flowed from the transportation pipe105 while being chemically reacted by the discharge in a mixture of saidmaterials to thereby effectively afford a reaction product (HX), whichis successively introduced into the film forming space A. As a result,there is formed a A-Si:H:F thin film on the substrate 104 at a highdeposition rate and with a high raw material gas utilization efficiency.

The film forming process using the apparatus shown in FIG. 4 to form,for example, a A-Si:C:H:F thin film is carried out in the following way.

That is, the film forming chamber 102, the space D and the space C areevacuated by opening the main valve of the exhaust pipe 101' to bringthe chamber and other spaces to a desired vacuum. Then the heater 110 isactivated to uniformly heat the substrate 104 to about 300° C., and itis kept at this temperature. At the same time, SiF₄ gas and CF₄ gas arefed at respective flow rates of 10 SCCM and 30 SCCM into the space D andthen into the film forming space A through the space E. Concurrently, H₂gas is fed at a flow rate of 20 SCCM into the space C and then into thefilm forming space A through the space E. After the flow rates of theabove gases became stable, the vacuum of the film forming space A isbrought to and kept at about 0.5 Torr by regulating the main valve ofthe exhaust pipe 101'.

After the vacuum of the film forming space A became stable, themicrowave power source is switched on to apply a discharge energy of adesired power into the space C through the microwave energy applyingapplicator 107 to generate the active species (H), i.e. H^(*) (hydrogenradical), which is successively flowed into the space E.

At the same time, the microwave power source is switched on to apply adischarge energy of a desired power into the space D through themicrowave energy applying applicator to thereby activate SiF₄ and CF₄ togenerate fluorine series radicals such as SiF₂ ^(*) from SiF₄ andanother kinds of series radicals such as CF₂ ^(*) from CF₄, which arealso successively flowed into the space E.

In t he above space C, the H₂ gas as introduced therein is almostconverted to hydrogen radical (H^(*)). However, as above described, someof the H₂ gas will be remained without activated therein and is flowedinto the space E. And some of the hydrogen radical will be deactivatedto be H₂, H, etc. during transportation to the space E, and suchdeactivated materials are also flowed into the space E.

Therefore, a mixture of the hydrogen radical (H^(*)), deactivatedmaterials caused therefrom and the remaining unactivated H₂ gas isflowed into the space E.

As for the above SiF₄ gas and CF₄ gas, they are almost activated in thespace D. However, some of them will be remained without activatedtherein.

And some of the activated products will be deactivated to return to theoriginal SiF₄ and CF₄ during their transportation to the space E. Inthis respect, a mixture of radicals (SiF₂ ^(*), CF₂ ^(*), etc.), SiF₄and CF₄ is flowed into the space E. The materials thus arrived in thespace E are mixed while being chemically reacted by the discharge in amixture of said materials to thereby effectively afford a reactionproduct (HX), which is successively introduced into the film formingspace. As a result, there is formed a A-Si:C:H:F thin film on thesubstrate 104 at a high deposition rate and with a high raw material gasutilization efficiency.

The film forming process using the apparatus shown in FIG. 5 and thatusing the apparatus shown in FIG. 5 are carried out in a similar way asin the case of using the apparatus shown in FIG. 4. And, in any of thesecases, there may be formed a desired thin film at a high deposition rateand with a high raw material utilization efficiency.

As above detailed, according to this invention, a film forming material(HX) capable of directly contributing to the formation of a functionaldeposited thin film on a substrate in an substantially enclosed filmforming space is firstly formed by mixing and chemically reacting thederivatives caused from the material (X) and the active species (H) asseparately introduced while applying a reaction promotion energy in asubstantially enclosed space isolated from the film forming space, andthe film forming material (HX) thus formed is successively introducedinto the film forming space wherein a substrate being maintained at anelevated temperature, to thereby form an objective functional depositedthin film on the surface of the substrate. Because of this, raw materialgases used are entirely and effectively consumed in forming the filmforming material (HX) in the foregoing space situated before the filmforming space, and it becomes possible to repeatedly produce a highquality functional deposited film at a high deposition rate and with ahigh raw material gas utilization efficiency.

PREFERRED EMBODIMENT OF THE INVENTION

The advantages of this invention are now described in more detail byreference to the following Examples, which are provided merely forillustrative purposes only, and are not intended to limit the scope ofthis invention.

In the following Examples, the term "microwave" means such that is of afrequency of 2.45 GHz except otherwise defined.

EXAMPLE 1

There was prepared a A-Si:H:F thin deposited film using the fabricationapparatus shown in FIG. 3. As the substrate 104, there was used aCorning's glass plate (product of Corning Glass Works Inc., USA).

The glass plate substrate was treated with a 1% solution of NaOH, washedwith water, and then air-dried. This glass plate substrate was thenfirmly attached to the surface of the substrate holder 103 in the filmforming chamber 102.

The film forming space A, the film forming raw material gastransportation pipe 105 and the space C were evacuated by opening themain valve of the exhaust pipe 101'to bring the film forming space andother spaces to a vacuum of 1×10⁻⁵ Torr. Then the heater 110 wasactivated to uniformly heat the substrate 104 to about 300° C., and itwas kept at this temperature. At the same time, SiF ₄ gas was fed at aflow rate of 30 SCCM into the transportation pipe 105 and then into thefilm forming space A through the space B. Concurrently, H₂ gas was fedat a flow rate of 20 SCCM into the active species (H) generation space Cand then into the film forming space A through the space B. After theflow rates of the two gases became stable, the vacuum of the filmforming space A was brought to and kept at a vacuum of about 0.5 Torr byregulating the main valve of the exhaust pipe 101'.

After the vacuum of the film forming space A became stable, themicrowave power source was switched on to apply a microwave energy of apower of 200 W/cm² into the active species (H) generation space Cthrough the microwave energy applying applicator 107.

Concurrently, the microwave power source was switched on to apply amicrowave energy of 50 W/cm² into the space E through the microwaveenergy applying applicator 302. After this state being maintained forabout 90 minutes, there was deposited a A-Si:H:F film (Sample No. 1-1B)on t he glass plate substrate 104.

The above procedures were repeated to thereby prepare further foursamples (Samples Nos. 1-2B to 1-5B).

Then, there were prepared five comparative samples (Samples Nos. 1-1A to1-1A) by repeating the above procedures except that there was notapplied any reaction promotion energy into the space E.

As for every resultant sample, there were examined a deposition rateD.R. (Å/sec.), a raw material gas utilization efficiency and a darkconductivity σd(Ω⁻¹ cm⁻¹

The results obtained were shown in Table 1.

In other experiment, it was tried to form a A-Si:H:F film by repeatingthe foregoing procedures except that there was not applied anyactivation energy into the active species (H) generation space but therewas applied a microwave energy of 200 W/cm² into the space E.

However, there was not found any film deposition on the glass platesubstrate.

As Table 1 illustrates, it is understood that there are unevennesses inthe deposition rate (D.R.) and the dark conductivity (σd) among the fivecomparative samples 1-1A to 1-5A and it is questionable to repeatedlyand stably obtain a desired functional deposited film of uniform qualityby way of the known process.

On the other hand, as for the five samples 1-1B to 1-5B preparedaccording to the process of this invention, it is found that there aredesired evennesses in the deposition rate (D.R.) and the darkconductivity among all the five samples and because of this, the processof this invention makes it possible to mass-produce a desired functionaldeposited film of uniform quality. In addition to this, it is alsounderstood that the deposition rate in the case of the process accordingto this invention is larger than that in the case of the known processand the raw material gas utilization efficiency in the case of theprocess according to this invention is significantly large by 7.7 to129% over that in the case of the known process.

EXAMPLE 2

The procedures of Example 1 according to this invention were repeated,except that the flow rate of SiF₄ gas and that of H₂ gas were changed to30 SCCM and 50 SCCM respectively, and a microwave energy of 100 W/cm² asthe reaction promotion energy was supplied into the space E, to therebyprepare five samples (Samples Nos. 2-1B to 2-5B).

Then, the procedures of Example 1 according to the known process for thepreparation of a comparative sample were repeated except that the flowrate of SiF₄ gas and that of H₂ gas were changed to 30 SCCM and 50 SCCMrespectively, to thereby prepare five comparative samples (Samples Nos.2-1A to 2-5A).

As a result of examining the dark conductivity (σd) and the activatedenergy (Ea) for every sample, there were obtained the results as shownin Table 2.

And as a result of conducting the observation of a RHEED image(reflection high energy electron diffusion image in accordance with aconventional method, it was found as for the five Samples Nos. 2-1B to2-5B prepared according to the process of this invention that there isobtained an uniform spot image for any of the Samples Nos. 2-1B to 2-5Band every sample is of a polycrystal-Si:H:F film excelling inorientation. On the other hand, as for the Samples Nos. 2-1A to 2-5Aprepared by way of the known process, it was found that there appearingimages for some of them and spot images for some of them and because ofthis, it is difficult to repeatedly and stably prepare a deposited filmof uniform quality.

EXAMPLE 3

There was prepared a A-Si:C:H:F thin deposited film using thefabrication apparatus shown in FIG. 4.

The film forming space A, the space C and the space D were evacuated byopening the main valve of the exhaust pipe 101' to bring the chamber andother spaces to a vacuum of 1×10⁻⁵ Torr. Then the heater 110 wasactivated to uniformly heat the substrate 104, to about 300° C., and itwas kept at this temperature. At the same timer, SiF₄ gas and CF₄ gaswere at respective flow rates of 10 SCCM and 30 SCCM into the space Dand then into the film forming space A through the space B.Concurrently, H₂ gas was fed at a flow rate of 20 SCCM into the space Cand then into the film forming space A through the space B. After theflow rates of the above gases became stable, the vacuum of the filmforming space A was brought to and kept at a vacuum of about 0.7 Torr byregulating the main valve of the exhaust pipe 101'.

After the vacuum of the film forming space A became stable, themicrowave power source was switched on to apply a microwave energy of200 W/cm² into the space C through the microwave energy applyingapplicator 107.

At the same time, the microwave power source was switched on to apply amicrowave energy of 200 W/cm² into the space D through the microwaveenergy applying applicator 202.

Concurrently, the microwave power source was switched on to apply amicrowave energy of 100 W/cm² into the space E through the microwaveenergy applying applicator 402. After this state being maintained forabout 2 hours, there was deposited a A-Si:C:H:F film (Sample No. 3-1B)on a glass plate substrate.

The above procedures were repeated to thereby prepare further foursamples (Samples Nos. 3-2B to 3-5B).

Then, there were prepared five comparative samples (Samples Nos. 3-1A to3-5A) by repeating the above procedures except that there was notapplied any reaction promotion energy into the space E.

As a result of examining an optical band gap Egopt(eV) and depositionrate D.R.(Å/sec.) on every resultant sample, there were obtained theresults as shown in Table 3.

As Table 3 illustrates, it is understood that the Samples Nos. 3-1B to3-5B are all superior to the comparative Samples Nos. 3-1A to 3-5A withrespect to every evaluation item.

In addition it was found that the raw material gas utilizationefficiencies in the preparation of the Samples Nos. 3-1B to 3-5B aresuperior by 16.7 to 117% to those in the preparation of the comparativeSamples Nos. 3-1A to 3-5A.

EXAMPLE 4

In this example, there was used the fabrication apparatus shown in FIG.5.

That is, the procedures of Example 3 according to this invention wererepeated, except that the application of a reaction promotion energyinto the space F was carried out by means of the tungusten filament 502to which an electric current of 5A being flowed, to thereby prepare fiveASi:C:H:F film samples (Samples Nos. 4-1B to 4-5B).

Then, the above procedures were repeated, except that there was notsupplied the above reaction promotion energy into the space F, tothereby prepare five comparative samples (Samples Nos. 4-1A to 4-5A).

Every resultant sample was evaluated by way of the evaluationprocedures. As a result, there were obtained similar results to thoseshown in Table 3.

EXAMPLE 5

There was prepared a A-Si:H:F thin film deposited film using thefabrication apparatus shown in FIG. 6.

That is, the film forming space A, the space C and the space D wereevacuated by opening the main valve of the exhaust pipe 601' to bringthe chamber and other spaces to a vacuum of about 1×10⁻⁵ Torr. Then theheater 603' was activated to uniformly heat the substrate 604 to about300° C., and it was kept at this temperature. At the same time, SiF₄ gaswas fed at a flow rate of 30 SCCM into the space D and then into thefilm forming space A through the space E. Concurrently, H₂ gas was fedat a flow rate of 20 SCCM into the space C and then into the filmforming space A through the space E. After the flow rates of the twogases became stable, the vacuum of the film forming space A was broughtto and kept at a vacuum of about 0.7 Torr by regulating the main valveof the exhaust pipe 601'.

After the vacuum of the film forming space A became stable, themicrowave power source was switched on to apply a microwave energy of200 W/cm² into the space C through the microwave energy applyingapplicator 607.

Concurrently, the microwave power source was switched on to apply amicrowave energy of 50 W/cm² into the space E through the microwaveenergy applying applicator 609.

After this state being maintained for 90 minutes, there was deposited aA-Si:H:F film (Sample No. 5-1B).

The above procedures were repeated to thereby prepare further foursamples (Samples Nos. 5-2B to 5-5B).

Then, there were prepared five comparative samples (Samples Nos. 5-1A to5-5A) by repeating the above procedures except that there was notapplied any reaction promotion energy into the space E.

Every resultant sample was evaluated in accordance with the evaluationprocedures in Example 1.

As a result, there were obtained quite similar results to those inExample 1.

                                      TABLE 1    __________________________________________________________________________          In the case where micro-                          In the case where micro-                                        *Increase proprotion    Comparative          wave was not applied                      Sample                          wave of 50 W/cm.sup.2 was applied                                        in raw material gas    Sample No.          σd(Ω.sup.-1 cm.sup.-1)                D.R. (Å/sec)                      No. σd(Ω.sup.-1 cm.sup.-1)                                 D.R. (Å/sec)                                        utilization (%)    __________________________________________________________________________    1-1A  1 × 10.sup.-9                1.2   1-1B                          1 × 10.sup.-9                                 1.5    25    1-2A  5 × 10.sup.-6                0.8   1-2B                          2 × 10.sup.-9                                 1.5    87.5    1-3A  2 × 10.sup.-5                0.7   1-3B                          .sup. 5 × 10.sup.-10                                 1.6    129    1-4A  2 × 10.sup.-9                1.2   1-4B                          .sup. 8 × 10.sup.-10                                 1.5    25    1-5A  .sup. 5 × 10.sup.-10                1.3   1-5B                          2 × 10.sup.-9                                 1.4    7.7    __________________________________________________________________________     *relative figure against the figure in the comparative sample

                  TABLE 2    ______________________________________            In the case            In the case where            where microwave        microwave of 100    Comparative            was not applied                          Sample   W/cm.sup.2 was applied    Sample No.            σd(Ω.sup.-1 cm.sup.-1)                      E.sub.a (eV)                              No.    σd(Ω.sup.-1 cm.sup.-1)                                             E.sub.a (eV)    ______________________________________    2-1A    2.0 × 10.sup.-5                      0.42    2-1B   2.0 × 10.sup.-3                                             0.15    2-2A    5.0 × 10.sup.-4                      0.19    2-2B   1.0 × 10.sup.-3                                             0.17    2-3A    3.0 × 10.sup.-3                      0.13    2-3B   2.5 × 10.sup.-3                                             0.14    2-4A    5.0 × 10.sup.-6                      0.52    2-4B   8.0 × 10.sup.-4                                             0.16    2-5A    4.0 × 10.sup.-5                      0.38    2-5B   1.3 × 10.sup.-3                                             0.17    ______________________________________

                                      TABLE 3    __________________________________________________________________________          In the case where micro-                          In the case where micro-                                        *Increase proprotion    Comparative          wave was not applied                      Sample                          wave of 100 W/cm.sup.2 was applied                                        in raw material gas    Sample No.          E.sub.gopt (eV)                D.R. (Å/sec)                      No. E.sub.gopt (eV)                                 D.R. (Å/sec)                                        utilization (%)    __________________________________________________________________________    3-1A  2.1   1.2   3-1B                          2.2    1.4    16.7    3-2A  1.9   0.7   3-2B                          2.2    1.3    85.7    3-3A  1.8   0.6   3-3B                          2.1    1.3    117    3-4A  2.0   1.0   3-4B                          2.2    1.4    40    3-5A  1.9   1.0   3-5B                          2.1    1.3    30    __________________________________________________________________________     *relative figure against the figure in the comparative sample

What we claim is:
 1. A process for forming a functional deposited filmon a substrate,said process comprising the steps of:(a) applying anenergy to a first gaseous material (X) in a first reaction space to forma derivative (X') of said gaseous material (X), each of said firstgaseous material (X) and derivative gaseous material (X') beingcomprised of silicon or germanium atoms capable of constituting saiddeposited film; (b) activating a second gaseous material (A) by applyinga microwave energy from a source to said second gaseous material (A) ina second reaction space to form an active species (H), said activespecies (H) being reactive with at least one of said first gaseousmaterial (X) or said derivative gaseous material (X'); (C) forming agaseous reaction product (HX) in a third space by mixing said firstgaseous material (X) and said derivative gaseous material (X') with saidactive species (H) in said third space while supplying a reactionpromotion energy comprising a microwave energy from a source differentfrom the source supplying the microwave energy to said second gaseousmaterial (A) to said mixture of said first gaseous material (X), saidderivative gaseous material (X') and said active species (H), said thirdspace having an introduction portion for introducing said materials(X,X', H) and a successive region for mixing said materials (X,X', H);and (d) introducing said reaction product (HX) into a substantiallyenclosed film-forming space which is different from but connected tosaid third space such that said reaction product (HX) is directed tosaid substrate positioned in said film-forming space while beingmaintained at a desired temperature, to form said functional depositedfilm on said substrate.
 2. The process according to claim 1, wherein thefirst gaseous material (X) is at least one member selected from thegroup consisting of SiF₄, Si₂ F₆, Si₃ F₈, SiCl₄, Si₂ Cl₆, SiF₂ Cl₂, Si₂F₄ Cl₂, SiBr₂ F₂, Si₂ Br₆, Si₂ I₆, GeF₄, GeCl₄, (SiF₂)₃, (SiF₂)₄,(SiF₂)₅, (SiF₂)₆, (GeF₂)₄, (GeF₂)₅, and (GeF₂)₆ ; and the second gaseousmaterial (A) is at least one member selected from the group consistingof H₂, SiH₄, Si₂ H₆, Si₃ H₈, GeH₄, Ge₂ H₆, Ge₃ H₈, CH₄, C₂ H₆, C₃ H₈,SnH₄, SiH₂ Cl₂, SiH₃ Cl, SiHF₃, SiHCl₃, and SiHBr₃.
 3. The processaccording to claim 1, wherein the second gaseous material (A) ishydrogen gas.